/* pngwrite.c - general routines to write a PNG file
 *
 * Last changed in libpng 1.4.0 [January 3, 2010]
 * Copyright (c) 1998-2010 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

/* Get internal access to png.h */
#include "png.h"
#define PNG_NO_PEDANTIC_WARNINGS
#ifdef PNG_WRITE_SUPPORTED
    #include "pngpriv.h"

/* Writes all the PNG information.  This is the suggested way to use the
 * library.  If you have a new chunk to add, make a function to write it,
 * and put it in the correct location here.  If you want the chunk written
 * after the image data, put it in png_write_end().  I strongly encourage
 * you to supply a PNG_INFO_ flag, and check info_ptr->valid before writing
 * the chunk, as that will keep the code from breaking if you want to just
 * write a plain PNG file.  If you have long comments, I suggest writing
 * them in png_write_end(), and compressing them.
 */
void PNGAPI
png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
{
    png_debug(1, "in png_write_info_before_PLTE");

    if (png_ptr == NULL || info_ptr == NULL)
        return;
    if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
    {
        /* Write PNG signature */
        png_write_sig(png_ptr);
        #ifdef PNG_MNG_FEATURES_SUPPORTED
        if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) && \
            (png_ptr->mng_features_permitted))
        {
            png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
            png_ptr->mng_features_permitted = 0;
        }
        #endif
        /* Write IHDR information. */
        png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
                       info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
                       info_ptr->filter_type,
                       #ifdef PNG_WRITE_INTERLACING_SUPPORTED
                       info_ptr->interlace_type);
                       #else
                       0);
        #endif
        /* The rest of these check to see if the valid field has the appropriate
         * flag set, and if it does, writes the chunk.
         */
        #ifdef PNG_WRITE_gAMA_SUPPORTED
        if (info_ptr->valid & PNG_INFO_gAMA)
        {
            #ifdef PNG_FLOATING_POINT_SUPPORTED
            png_write_gAMA(png_ptr, info_ptr->gamma);
            #else
            #ifdef PNG_FIXED_POINT_SUPPORTED
            png_write_gAMA_fixed(png_ptr, info_ptr->int_gamma);
            #endif
            #endif
        }
        #endif
        #ifdef PNG_WRITE_sRGB_SUPPORTED
        if (info_ptr->valid & PNG_INFO_sRGB)
            png_write_sRGB(png_ptr, (int)info_ptr->srgb_intent);
        #endif
        #ifdef PNG_WRITE_iCCP_SUPPORTED
        if (info_ptr->valid & PNG_INFO_iCCP)
            png_write_iCCP(png_ptr, info_ptr->iccp_name, PNG_COMPRESSION_TYPE_BASE,
                           info_ptr->iccp_profile, (int)info_ptr->iccp_proflen);
        #endif
        #ifdef PNG_WRITE_sBIT_SUPPORTED
        if (info_ptr->valid & PNG_INFO_sBIT)
            png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
        #endif
        #ifdef PNG_WRITE_cHRM_SUPPORTED
        if (info_ptr->valid & PNG_INFO_cHRM)
        {
            #ifdef PNG_FLOATING_POINT_SUPPORTED
            png_write_cHRM(png_ptr,
                           info_ptr->x_white, info_ptr->y_white,
                           info_ptr->x_red, info_ptr->y_red,
                           info_ptr->x_green, info_ptr->y_green,
                           info_ptr->x_blue, info_ptr->y_blue);
            #else
            #ifdef PNG_FIXED_POINT_SUPPORTED
            png_write_cHRM_fixed(png_ptr,
                                 info_ptr->int_x_white, info_ptr->int_y_white,
                                 info_ptr->int_x_red, info_ptr->int_y_red,
                                 info_ptr->int_x_green, info_ptr->int_y_green,
                                 info_ptr->int_x_blue, info_ptr->int_y_blue);
            #endif
            #endif
        }
        #endif
        #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
        if (info_ptr->unknown_chunks_num)
        {
            png_unknown_chunk* up;

            png_debug(5, "writing extra chunks");

            for (up = info_ptr->unknown_chunks;
                 up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
                 up++)
            {
                int keep = png_handle_as_unknown(png_ptr, up->name);
                if (keep != PNG_HANDLE_CHUNK_NEVER &&
                    up->location && !(up->location & PNG_HAVE_PLTE) &&
                    !(up->location & PNG_HAVE_IDAT) &&
                    ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
                     (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
                {
                    if (up->size == 0)
                        png_warning(png_ptr, "Writing zero-length unknown chunk");
                    png_write_chunk(png_ptr, up->name, up->data, up->size);
                }
            }
        }
        #endif
        png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
    }
}

void PNGAPI
png_write_info(png_structp png_ptr, png_infop info_ptr)
{
    #if defined (PNG_WRITE_TEXT_SUPPORTED) || defined (PNG_WRITE_sPLT_SUPPORTED)
    int i;
    #endif

    png_debug(1, "in png_write_info");

    if (png_ptr == NULL || info_ptr == NULL)
        return;

    png_write_info_before_PLTE(png_ptr, info_ptr);

    if (info_ptr->valid & PNG_INFO_PLTE)
        png_write_PLTE(png_ptr, info_ptr->palette,
                       (png_uint_32)info_ptr->num_palette);
    else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
        png_error(png_ptr, "Valid palette required for paletted images");

    #ifdef PNG_WRITE_tRNS_SUPPORTED
    if (info_ptr->valid & PNG_INFO_tRNS)
    {
        #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
        /* Invert the alpha channel (in tRNS) */
        if ((png_ptr->transformations & PNG_INVERT_ALPHA) &&
            info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
        {
            int j;
            for (j = 0; j < (int)info_ptr->num_trans; j++)
                info_ptr->trans_alpha[j] = (png_byte)(255 - info_ptr->trans_alpha[j]);
        }
        #endif
        png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
                       info_ptr->num_trans, info_ptr->color_type);
    }
    #endif
    #ifdef PNG_WRITE_bKGD_SUPPORTED
    if (info_ptr->valid & PNG_INFO_bKGD)
        png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
    #endif
    #ifdef PNG_WRITE_hIST_SUPPORTED
    if (info_ptr->valid & PNG_INFO_hIST)
        png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
    #endif
    #ifdef PNG_WRITE_oFFs_SUPPORTED
    if (info_ptr->valid & PNG_INFO_oFFs)
        png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
                       info_ptr->offset_unit_type);
    #endif
    #ifdef PNG_WRITE_pCAL_SUPPORTED
    if (info_ptr->valid & PNG_INFO_pCAL)
        png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
                       info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
                       info_ptr->pcal_units, info_ptr->pcal_params);
    #endif

    #ifdef PNG_sCAL_SUPPORTED
    if (info_ptr->valid & PNG_INFO_sCAL)
    #ifdef PNG_WRITE_sCAL_SUPPORTED
    #if defined (PNG_FLOATING_POINT_SUPPORTED) && defined (PNG_STDIO_SUPPORTED)
        png_write_sCAL(png_ptr, (int)info_ptr->scal_unit,
                       info_ptr->scal_pixel_width, info_ptr->scal_pixel_height);
    #else /* !FLOATING_POINT */
    #ifdef PNG_FIXED_POINT_SUPPORTED
        png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
                         info_ptr->scal_s_width, info_ptr->scal_s_height);
    #endif /* FIXED_POINT */
    #endif /* FLOATING_POINT */
    #else /* !WRITE_sCAL */
        png_warning(png_ptr,
                    "png_write_sCAL not supported; sCAL chunk not written");
    #endif /* WRITE_sCAL */
    #endif /* sCAL */

    #ifdef PNG_WRITE_pHYs_SUPPORTED
    if (info_ptr->valid & PNG_INFO_pHYs)
        png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
                       info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
    #endif /* pHYs */

    #ifdef PNG_WRITE_tIME_SUPPORTED
    if (info_ptr->valid & PNG_INFO_tIME)
    {
        png_write_tIME(png_ptr, &(info_ptr->mod_time));
        png_ptr->mode |= PNG_WROTE_tIME;
    }
    #endif /* tIME */

    #ifdef PNG_WRITE_sPLT_SUPPORTED
    if (info_ptr->valid & PNG_INFO_sPLT)
        for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
            png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
    #endif /* sPLT */

    #ifdef PNG_WRITE_TEXT_SUPPORTED
    /* Check to see if we need to write text chunks */
    for (i = 0; i < info_ptr->num_text; i++)
    {
        png_debug2(2, "Writing header text chunk %d, type %d", i,
                   info_ptr->text[i].compression);
        /* An internationalized chunk? */
        if (info_ptr->text[i].compression > 0)
        {
            #ifdef PNG_WRITE_iTXt_SUPPORTED
            /* Write international chunk */
            png_write_iTXt(png_ptr,
                           info_ptr->text[i].compression,
                           info_ptr->text[i].key,
                           info_ptr->text[i].lang,
                           info_ptr->text[i].lang_key,
                           info_ptr->text[i].text);
            #else
            png_warning(png_ptr, "Unable to write international text");
            #endif
            /* Mark this chunk as written */
            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
        }
        /* If we want a compressed text chunk */
        else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
        {
            #ifdef PNG_WRITE_zTXt_SUPPORTED
            /* Write compressed chunk */
            png_write_zTXt(png_ptr, info_ptr->text[i].key,
                           info_ptr->text[i].text, 0,
                           info_ptr->text[i].compression);
            #else
            png_warning(png_ptr, "Unable to write compressed text");
            #endif
            /* Mark this chunk as written */
            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
        }
        else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
        {
            #ifdef PNG_WRITE_tEXt_SUPPORTED
            /* Write uncompressed chunk */
            png_write_tEXt(png_ptr, info_ptr->text[i].key,
                           info_ptr->text[i].text,
                           0);
            /* Mark this chunk as written */
            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
            #else
            /* Can't get here */
            png_warning(png_ptr, "Unable to write uncompressed text");
            #endif
        }
    }
    #endif /* tEXt */

    #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
    if (info_ptr->unknown_chunks_num)
    {
        png_unknown_chunk* up;

        png_debug(5, "writing extra chunks");

        for (up = info_ptr->unknown_chunks;
             up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
             up++)
        {
            int keep = png_handle_as_unknown(png_ptr, up->name);
            if (keep != PNG_HANDLE_CHUNK_NEVER &&
                up->location && (up->location & PNG_HAVE_PLTE) &&
                !(up->location & PNG_HAVE_IDAT) &&
                ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
                 (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
            {
                png_write_chunk(png_ptr, up->name, up->data, up->size);
            }
        }
    }
    #endif
}

/* Writes the end of the PNG file.  If you don't want to write comments or
 * time information, you can pass NULL for info.  If you already wrote these
 * in png_write_info(), do not write them again here.  If you have long
 * comments, I suggest writing them here, and compressing them.
 */
void PNGAPI
png_write_end(png_structp png_ptr, png_infop info_ptr)
{
    png_debug(1, "in png_write_end");

    if (png_ptr == NULL)
        return;
    if (!(png_ptr->mode & PNG_HAVE_IDAT))
        png_error(png_ptr, "No IDATs written into file");

    /* See if user wants us to write information chunks */
    if (info_ptr != NULL)
    {
        #ifdef PNG_WRITE_TEXT_SUPPORTED
        int i; /* local index variable */
        #endif
        #ifdef PNG_WRITE_tIME_SUPPORTED
        /* Check to see if user has supplied a time chunk */
        if ((info_ptr->valid & PNG_INFO_tIME) &&
            !(png_ptr->mode & PNG_WROTE_tIME))
            png_write_tIME(png_ptr, &(info_ptr->mod_time));
        #endif
        #ifdef PNG_WRITE_TEXT_SUPPORTED
        /* Loop through comment chunks */
        for (i = 0; i < info_ptr->num_text; i++)
        {
            png_debug2(2, "Writing trailer text chunk %d, type %d", i,
                       info_ptr->text[i].compression);
            /* An internationalized chunk? */
            if (info_ptr->text[i].compression > 0)
            {
                #ifdef PNG_WRITE_iTXt_SUPPORTED
                /* Write international chunk */
                png_write_iTXt(png_ptr,
                               info_ptr->text[i].compression,
                               info_ptr->text[i].key,
                               info_ptr->text[i].lang,
                               info_ptr->text[i].lang_key,
                               info_ptr->text[i].text);
                #else
                png_warning(png_ptr, "Unable to write international text");
                #endif
                /* Mark this chunk as written */
                info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
            }
            else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
            {
                #ifdef PNG_WRITE_zTXt_SUPPORTED
                /* Write compressed chunk */
                png_write_zTXt(png_ptr, info_ptr->text[i].key,
                               info_ptr->text[i].text, 0,
                               info_ptr->text[i].compression);
                #else
                png_warning(png_ptr, "Unable to write compressed text");
                #endif
                /* Mark this chunk as written */
                info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
            }
            else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
            {
                #ifdef PNG_WRITE_tEXt_SUPPORTED
                /* Write uncompressed chunk */
                png_write_tEXt(png_ptr, info_ptr->text[i].key,
                               info_ptr->text[i].text, 0);
                #else
                png_warning(png_ptr, "Unable to write uncompressed text");
                #endif

                /* Mark this chunk as written */
                info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
            }
        }
        #endif
        #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
        if (info_ptr->unknown_chunks_num)
        {
            png_unknown_chunk* up;

            png_debug(5, "writing extra chunks");

            for (up = info_ptr->unknown_chunks;
                 up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
                 up++)
            {
                int keep = png_handle_as_unknown(png_ptr, up->name);
                if (keep != PNG_HANDLE_CHUNK_NEVER &&
                    up->location && (up->location & PNG_AFTER_IDAT) &&
                    ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
                     (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
                {
                    png_write_chunk(png_ptr, up->name, up->data, up->size);
                }
            }
        }
        #endif
    }

    png_ptr->mode |= PNG_AFTER_IDAT;

    /* Write end of PNG file */
    png_write_IEND(png_ptr);
    /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
     * and restored again in libpng-1.2.30, may cause some applications that
     * do not set png_ptr->output_flush_fn to crash.  If your application
     * experiences a problem, please try building libpng with
     * PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
     * png-mng-implement at lists.sf.net .
     */
    #ifdef PNG_WRITE_FLUSH_SUPPORTED
    #ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
    png_flush(png_ptr);
    #endif
    #endif
}

    #ifdef PNG_CONVERT_tIME_SUPPORTED
/* "tm" structure is not supported on WindowsCE */
void PNGAPI
png_convert_from_struct_tm(png_timep ptime, struct tm FAR* ttime)
{
    png_debug(1, "in png_convert_from_struct_tm");

    ptime->year = (png_uint_16)(1900 + ttime->tm_year);
    ptime->month = (png_byte)(ttime->tm_mon + 1);
    ptime->day = (png_byte)ttime->tm_mday;
    ptime->hour = (png_byte)ttime->tm_hour;
    ptime->minute = (png_byte)ttime->tm_min;
    ptime->second = (png_byte)ttime->tm_sec;
}

void PNGAPI
png_convert_from_time_t(png_timep ptime, time_t ttime)
{
    struct tm* tbuf;

    png_debug(1, "in png_convert_from_time_t");

    tbuf = gmtime(&ttime);
    png_convert_from_struct_tm(ptime, tbuf);
}
    #endif

/* Initialize png_ptr structure, and allocate any memory needed */
png_structp PNGAPI
png_create_write_struct(png_const_charp user_png_ver, png_voidp error_ptr,
                        png_error_ptr error_fn, png_error_ptr warn_fn)
{
    #ifdef PNG_USER_MEM_SUPPORTED
    return (png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
                                      warn_fn, NULL, NULL, NULL));
}

/* Alternate initialize png_ptr structure, and allocate any memory needed */
png_structp PNGAPI
png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
                          png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
                          png_malloc_ptr malloc_fn, png_free_ptr free_fn)
{
    #endif /* PNG_USER_MEM_SUPPORTED */
    volatile int png_cleanup_needed = 0;
    #ifdef PNG_SETJMP_SUPPORTED
    volatile
    #endif
    png_structp png_ptr;
    #ifdef PNG_SETJMP_SUPPORTED
    #ifdef USE_FAR_KEYWORD
    jmp_buf jmpbuf;
    #endif
    #endif
    int i;

    png_debug(1, "in png_create_write_struct");

    #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
                                               (png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);
    #else
    png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
    #endif /* PNG_USER_MEM_SUPPORTED */
    if (png_ptr == NULL)
        return (NULL);

    /* Added at libpng-1.2.6 */
    #ifdef PNG_SET_USER_LIMITS_SUPPORTED
    png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
    png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
    #endif

    #ifdef PNG_SETJMP_SUPPORTED
    /* Applications that neglect to set up their own setjmp() and then
       encounter a png_error() will longjmp here.  Since the jmpbuf is
       then meaningless we abort instead of returning. */
    #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
    #else
    if (setjmp(png_jmpbuf(png_ptr))) /* sets longjmp to match setjmp */
    #endif
    #ifdef USE_FAR_KEYWORD
        png_memcpy(png_jmpbuf(png_ptr), jmpbuf, png_sizeof(jmp_buf));
    #endif
        PNG_ABORT();
    #endif

    #ifdef PNG_USER_MEM_SUPPORTED
    png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
    #endif /* PNG_USER_MEM_SUPPORTED */
    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);

    if (user_png_ver)
    {
        i = 0;
        do
        {
            if (user_png_ver[i] != png_libpng_ver[i])
                png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
        }
        while (png_libpng_ver[i++]);
    }

    if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
    {
        /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
         * we must recompile any applications that use any older library version.
         * For versions after libpng 1.0, we will be compatible, so we need
         * only check the first digit.
         */
        if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
            (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
            (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
        {
            #ifdef PNG_STDIO_SUPPORTED
            char msg[80];
            if (user_png_ver)
            {
                png_snprintf(msg, 80,
                             "Application was compiled with png.h from libpng-%.20s",
                             user_png_ver);
                png_warning(png_ptr, msg);
            }
            png_snprintf(msg, 80,
                         "Application  is  running with png.c from libpng-%.20s",
                         png_libpng_ver);
            png_warning(png_ptr, msg);
            #endif
            #ifdef PNG_ERROR_NUMBERS_SUPPORTED
            png_ptr->flags = 0;
            #endif
            png_warning(png_ptr,
                        "Incompatible libpng version in application and library");
            png_cleanup_needed = 1;
        }
    }

    /* Initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
    if (!png_cleanup_needed)
    {
        png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr,
                                                   png_ptr->zbuf_size);
        if (png_ptr->zbuf == NULL)
            png_cleanup_needed = 1;
    }
    if (png_cleanup_needed)
    {
        /* Clean up PNG structure and deallocate any memory. */
        png_free(png_ptr, png_ptr->zbuf);
        png_ptr->zbuf = NULL;
        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)png_ptr,
                             (png_free_ptr)free_fn, (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)png_ptr);
        #endif
        return (NULL);
    }

    png_set_write_fn(png_ptr, NULL, NULL, NULL);

    #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
                              1, NULL, NULL);
    #endif

    return (png_ptr);
}


/* Write a few rows of image data.  If the image is interlaced,
 * either you will have to write the 7 sub images, or, if you
 * have called png_set_interlace_handling(), you will have to
 * "write" the image seven times.
 */
void PNGAPI
png_write_rows(png_structp png_ptr, png_bytepp row,
               png_uint_32 num_rows)
{
    png_uint_32 i; /* row counter */
    png_bytepp rp; /* row pointer */

    png_debug(1, "in png_write_rows");

    if (png_ptr == NULL)
        return;

    /* Loop through the rows */
    for (i = 0, rp = row; i < num_rows; i++, rp++)
    {
        png_write_row(png_ptr, *rp);
    }
}

/* Write the image.  You only need to call this function once, even
 * if you are writing an interlaced image.
 */
void PNGAPI
png_write_image(png_structp png_ptr, png_bytepp image)
{
    png_uint_32 i; /* row index */
    int pass, num_pass; /* pass variables */
    png_bytepp rp; /* points to current row */

    if (png_ptr == NULL)
        return;

    png_debug(1, "in png_write_image");

    #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Initialize interlace handling.  If image is not interlaced,
     * this will set pass to 1
     */
    num_pass = png_set_interlace_handling(png_ptr);
    #else
    num_pass = 1;
    #endif
    /* Loop through passes */
    for (pass = 0; pass < num_pass; pass++)
    {
        /* Loop through image */
        for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
        {
            png_write_row(png_ptr, *rp);
        }
    }
}

/* Called by user to write a row of image data */
void PNGAPI
png_write_row(png_structp png_ptr, png_bytep row)
{
    if (png_ptr == NULL)
        return;

    png_debug2(1, "in png_write_row (row %ld, pass %d)",
               png_ptr->row_number, png_ptr->pass);

    /* Initialize transformations and other stuff if first time */
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
        /* Make sure we wrote the header info */
        if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
            png_error(png_ptr,
                      "png_write_info was never called before png_write_row");

        /* Check for transforms that have been set but were defined out */
        #if !defined (PNG_WRITE_INVERT_SUPPORTED) && defined (PNG_READ_INVERT_SUPPORTED)
        if (png_ptr->transformations & PNG_INVERT_MONO)
            png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
        #endif
        #if !defined (PNG_WRITE_FILLER_SUPPORTED) && defined (PNG_READ_FILLER_SUPPORTED)
        if (png_ptr->transformations & PNG_FILLER)
            png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
        #endif
        #if !defined (PNG_WRITE_PACKSWAP_SUPPORTED) && \
        defined (PNG_READ_PACKSWAP_SUPPORTED)
        if (png_ptr->transformations & PNG_PACKSWAP)
            png_warning(png_ptr,
                        "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
        #endif
        #if !defined (PNG_WRITE_PACK_SUPPORTED) && defined (PNG_READ_PACK_SUPPORTED)
        if (png_ptr->transformations & PNG_PACK)
            png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
        #endif
        #if !defined (PNG_WRITE_SHIFT_SUPPORTED) && defined (PNG_READ_SHIFT_SUPPORTED)
        if (png_ptr->transformations & PNG_SHIFT)
            png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
        #endif
        #if !defined (PNG_WRITE_BGR_SUPPORTED) && defined (PNG_READ_BGR_SUPPORTED)
        if (png_ptr->transformations & PNG_BGR)
            png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
        #endif
        #if !defined (PNG_WRITE_SWAP_SUPPORTED) && defined (PNG_READ_SWAP_SUPPORTED)
        if (png_ptr->transformations & PNG_SWAP_BYTES)
            png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
        #endif

        png_write_start_row(png_ptr);
    }

    #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced and not interested in row, return */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
        switch (png_ptr->pass)
        {
            case 0:
                if (png_ptr->row_number & 0x07)
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
            case 1:
                if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
            case 2:
                if ((png_ptr->row_number & 0x07) != 4)
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
            case 3:
                if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
            case 4:
                if ((png_ptr->row_number & 0x03) != 2)
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
            case 5:
                if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
            case 6:
                if (!(png_ptr->row_number & 0x01))
                {
                    png_write_finish_row(png_ptr);
                    return;
                }
                break;
        }
    }
    #endif

    /* Set up row info for transformations */
    png_ptr->row_info.color_type = png_ptr->color_type;
    png_ptr->row_info.width = png_ptr->usr_width;
    png_ptr->row_info.channels = png_ptr->usr_channels;
    png_ptr->row_info.bit_depth = png_ptr->usr_bit_depth;
    png_ptr->row_info.pixel_depth = (png_byte)(png_ptr->row_info.bit_depth *
                                               png_ptr->row_info.channels);

    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
                                              png_ptr->row_info.width);

    png_debug1(3, "row_info->color_type = %d", png_ptr->row_info.color_type);
    png_debug1(3, "row_info->width = %lu", png_ptr->row_info.width);
    png_debug1(3, "row_info->channels = %d", png_ptr->row_info.channels);
    png_debug1(3, "row_info->bit_depth = %d", png_ptr->row_info.bit_depth);
    png_debug1(3, "row_info->pixel_depth = %d", png_ptr->row_info.pixel_depth);
    png_debug1(3, "row_info->rowbytes = %lu", png_ptr->row_info.rowbytes);

    /* Copy user's row into buffer, leaving room for filter byte. */
    png_memcpy(png_ptr->row_buf + 1, row, png_ptr->row_info.rowbytes);

    #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Handle interlacing */
    if (png_ptr->interlaced && png_ptr->pass < 6 &&
        (png_ptr->transformations & PNG_INTERLACE))
    {
        png_do_write_interlace(&(png_ptr->row_info),
                               png_ptr->row_buf + 1, png_ptr->pass);
        /* This should always get caught above, but still ... */
        if (!(png_ptr->row_info.width))
        {
            png_write_finish_row(png_ptr);
            return;
        }
    }
    #endif

    /* Handle other transformations */
    if (png_ptr->transformations)
        png_do_write_transformations(png_ptr);

    #ifdef PNG_MNG_FEATURES_SUPPORTED
    /* Write filter_method 64 (intrapixel differencing) only if
     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
     * 2. Libpng did not write a PNG signature (this filter_method is only
     *    used in PNG datastreams that are embedded in MNG datastreams) and
     * 3. The application called png_permit_mng_features with a mask that
     *    included PNG_FLAG_MNG_FILTER_64 and
     * 4. The filter_method is 64 and
     * 5. The color_type is RGB or RGBA
     */
    if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
    {
        /* Intrapixel differencing */
        png_do_write_intrapixel(&(png_ptr->row_info), png_ptr->row_buf + 1);
    }
    #endif

    /* Find a filter if necessary, filter the row and write it out. */
    png_write_find_filter(png_ptr, &(png_ptr->row_info));

    if (png_ptr->write_row_fn != NULL)
        (*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
}

    #ifdef PNG_WRITE_FLUSH_SUPPORTED
/* Set the automatic flush interval or 0 to turn flushing off */
void PNGAPI
png_set_flush(png_structp png_ptr, int nrows)
{
    png_debug(1, "in png_set_flush");

    if (png_ptr == NULL)
        return;
    png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
}

/* Flush the current output buffers now */
void PNGAPI
png_write_flush(png_structp png_ptr)
{
    int wrote_IDAT;

    png_debug(1, "in png_write_flush");

    if (png_ptr == NULL)
        return;
    /* We have already written out all of the data */
    if (png_ptr->row_number >= png_ptr->num_rows)
        return;

    do
    {
        int ret;

        /* Compress the data */
        ret = deflate(&png_ptr->zstream, Z_SYNC_FLUSH);
        wrote_IDAT = 0;

        /* Check for compression errors */
        if (ret != Z_OK)
        {
            if (png_ptr->zstream.msg != NULL)
                png_error(png_ptr, png_ptr->zstream.msg);
            else
                png_error(png_ptr, "zlib error");
        }

        if (!(png_ptr->zstream.avail_out))
        {
            /* Write the IDAT and reset the zlib output buffer */
            png_write_IDAT(png_ptr, png_ptr->zbuf,
                           png_ptr->zbuf_size);
            png_ptr->zstream.next_out = png_ptr->zbuf;
            png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
            wrote_IDAT = 1;
        }
    }
    while (wrote_IDAT == 1);

    /* If there is any data left to be output, write it into a new IDAT */
    if (png_ptr->zbuf_size != png_ptr->zstream.avail_out)
    {
        /* Write the IDAT and reset the zlib output buffer */
        png_write_IDAT(png_ptr, png_ptr->zbuf,
                       png_ptr->zbuf_size - png_ptr->zstream.avail_out);
        png_ptr->zstream.next_out = png_ptr->zbuf;
        png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
    }
    png_ptr->flush_rows = 0;
    png_flush(png_ptr);
}
    #endif /* PNG_WRITE_FLUSH_SUPPORTED */

/* Free all memory used by the write */
void PNGAPI
png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
{
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL;
    #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn = NULL;
    png_voidp mem_ptr = NULL;
    #endif

    png_debug(1, "in png_destroy_write_struct");

    if (png_ptr_ptr != NULL)
    {
        png_ptr = *png_ptr_ptr;
        #ifdef PNG_USER_MEM_SUPPORTED
        free_fn = png_ptr->free_fn;
        mem_ptr = png_ptr->mem_ptr;
        #endif
    }

    #ifdef PNG_USER_MEM_SUPPORTED
    if (png_ptr != NULL)
    {
        free_fn = png_ptr->free_fn;
        mem_ptr = png_ptr->mem_ptr;
    }
    #endif

    if (info_ptr_ptr != NULL)
        info_ptr = *info_ptr_ptr;

    if (info_ptr != NULL)
    {
        if (png_ptr != NULL)
        {
            png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);

            #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
            if (png_ptr->num_chunk_list)
            {
                png_free(png_ptr, png_ptr->chunk_list);
                png_ptr->num_chunk_list = 0;
            }
            #endif
        }

        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
                             (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)info_ptr);
        #endif
        *info_ptr_ptr = NULL;
    }

    if (png_ptr != NULL)
    {
        png_write_destroy(png_ptr);
        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
                             (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)png_ptr);
        #endif
        *png_ptr_ptr = NULL;
    }
}


/* Free any memory used in png_ptr struct (old method) */
void /* PRIVATE */
png_write_destroy(png_structp png_ptr)
{
    #ifdef PNG_SETJMP_SUPPORTED
    jmp_buf tmp_jmp; /* Save jump buffer */
    #endif
    png_error_ptr error_fn;
    png_error_ptr warning_fn;
    png_voidp error_ptr;
    #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn;
    #endif

    png_debug(1, "in png_write_destroy");

    /* Free any memory zlib uses */
    deflateEnd(&png_ptr->zstream);

    /* Free our memory.  png_free checks NULL for us. */
    png_free(png_ptr, png_ptr->zbuf);
    png_free(png_ptr, png_ptr->row_buf);
    #ifdef PNG_WRITE_FILTER_SUPPORTED
    png_free(png_ptr, png_ptr->prev_row);
    png_free(png_ptr, png_ptr->sub_row);
    png_free(png_ptr, png_ptr->up_row);
    png_free(png_ptr, png_ptr->avg_row);
    png_free(png_ptr, png_ptr->paeth_row);
    #endif

    #ifdef PNG_TIME_RFC1123_SUPPORTED
    png_free(png_ptr, png_ptr->time_buffer);
    #endif

    #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_free(png_ptr, png_ptr->prev_filters);
    png_free(png_ptr, png_ptr->filter_weights);
    png_free(png_ptr, png_ptr->inv_filter_weights);
    png_free(png_ptr, png_ptr->filter_costs);
    png_free(png_ptr, png_ptr->inv_filter_costs);
    #endif

    #ifdef PNG_SETJMP_SUPPORTED
    /* Reset structure */
    png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
    #endif

    error_fn = png_ptr->error_fn;
    warning_fn = png_ptr->warning_fn;
    error_ptr = png_ptr->error_ptr;
    #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
    #endif

    png_memset(png_ptr, 0, png_sizeof(png_struct));

    png_ptr->error_fn = error_fn;
    png_ptr->warning_fn = warning_fn;
    png_ptr->error_ptr = error_ptr;
    #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr->free_fn = free_fn;
    #endif

    #ifdef PNG_SETJMP_SUPPORTED
    png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));
    #endif
}

/* Allow the application to select one or more row filters to use. */
void PNGAPI
png_set_filter(png_structp png_ptr, int method, int filters)
{
    png_debug(1, "in png_set_filter");

    if (png_ptr == NULL)
        return;
    #ifdef PNG_MNG_FEATURES_SUPPORTED
    if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
        (method == PNG_INTRAPIXEL_DIFFERENCING))
        method = PNG_FILTER_TYPE_BASE;
    #endif
    if (method == PNG_FILTER_TYPE_BASE)
    {
        switch (filters & (PNG_ALL_FILTERS | 0x07))
        {
            #ifdef PNG_WRITE_FILTER_SUPPORTED
            case 5:
            case 6:
            case 7: png_warning(png_ptr, "Unknown row filter for method 0");
            #endif /* PNG_WRITE_FILTER_SUPPORTED */
            case PNG_FILTER_VALUE_NONE:
                png_ptr->do_filter = PNG_FILTER_NONE; break;
                #ifdef PNG_WRITE_FILTER_SUPPORTED
            case PNG_FILTER_VALUE_SUB:
                png_ptr->do_filter = PNG_FILTER_SUB; break;
            case PNG_FILTER_VALUE_UP:
                png_ptr->do_filter = PNG_FILTER_UP; break;
            case PNG_FILTER_VALUE_AVG:
                png_ptr->do_filter = PNG_FILTER_AVG; break;
            case PNG_FILTER_VALUE_PAETH:
                png_ptr->do_filter = PNG_FILTER_PAETH; break;
            default: png_ptr->do_filter = (png_byte)filters; break;
                #else
            default: png_warning(png_ptr, "Unknown row filter for method 0");
                #endif /* PNG_WRITE_FILTER_SUPPORTED */
        }

        /* If we have allocated the row_buf, this means we have already started
         * with the image and we should have allocated all of the filter buffers
         * that have been selected.  If prev_row isn't already allocated, then
         * it is too late to start using the filters that need it, since we
         * will be missing the data in the previous row.  If an application
         * wants to start and stop using particular filters during compression,
         * it should start out with all of the filters, and then add and
         * remove them after the start of compression.
         */
        if (png_ptr->row_buf != NULL)
        {
            #ifdef PNG_WRITE_FILTER_SUPPORTED
            if ((png_ptr->do_filter & PNG_FILTER_SUB) && png_ptr->sub_row == NULL)
            {
                png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
                                                         (png_ptr->rowbytes + 1));
                png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
            }

            if ((png_ptr->do_filter & PNG_FILTER_UP) && png_ptr->up_row == NULL)
            {
                if (png_ptr->prev_row == NULL)
                {
                    png_warning(png_ptr, "Can't add Up filter after starting");
                    png_ptr->do_filter &= ~PNG_FILTER_UP;
                }
                else
                {
                    png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
                                                            (png_ptr->rowbytes + 1));
                    png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
                }
            }

            if ((png_ptr->do_filter & PNG_FILTER_AVG) && png_ptr->avg_row == NULL)
            {
                if (png_ptr->prev_row == NULL)
                {
                    png_warning(png_ptr, "Can't add Average filter after starting");
                    png_ptr->do_filter &= ~PNG_FILTER_AVG;
                }
                else
                {
                    png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
                                                             (png_ptr->rowbytes + 1));
                    png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
                }
            }

            if ((png_ptr->do_filter & PNG_FILTER_PAETH) &&
                png_ptr->paeth_row == NULL)
            {
                if (png_ptr->prev_row == NULL)
                {
                    png_warning(png_ptr, "Can't add Paeth filter after starting");
                    png_ptr->do_filter &= (png_byte)(~PNG_FILTER_PAETH);
                }
                else
                {
                    png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
                                                               (png_ptr->rowbytes + 1));
                    png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
                }
            }

            if (png_ptr->do_filter == PNG_NO_FILTERS)
            #endif /* PNG_WRITE_FILTER_SUPPORTED */
            png_ptr->do_filter = PNG_FILTER_NONE;
        }
    }
    else
        png_error(png_ptr, "Unknown custom filter method");
}

/* This allows us to influence the way in which libpng chooses the "best"
 * filter for the current scanline.  While the "minimum-sum-of-absolute-
 * differences metric is relatively fast and effective, there is some
 * question as to whether it can be improved upon by trying to keep the
 * filtered data going to zlib more consistent, hopefully resulting in
 * better compression.
 */
    #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED  /* GRR 970116 */
void PNGAPI
png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
                          int num_weights, png_doublep filter_weights,
                          png_doublep filter_costs)
{
    int i;

    png_debug(1, "in png_set_filter_heuristics");

    if (png_ptr == NULL)
        return;
    if (heuristic_method >= PNG_FILTER_HEURISTIC_LAST)
    {
        png_warning(png_ptr, "Unknown filter heuristic method");
        return;
    }

    if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT)
    {
        heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
    }

    if (num_weights < 0 || filter_weights == NULL ||
        heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
    {
        num_weights = 0;
    }

    png_ptr->num_prev_filters = (png_byte)num_weights;
    png_ptr->heuristic_method = (png_byte)heuristic_method;

    if (num_weights > 0)
    {
        if (png_ptr->prev_filters == NULL)
        {
            png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
                                                          (png_uint_32)(png_sizeof(png_byte) * num_weights));

            /* To make sure that the weighting starts out fairly */
            for (i = 0; i < num_weights; i++)
            {
                png_ptr->prev_filters[i] = 255;
            }
        }

        if (png_ptr->filter_weights == NULL)
        {
            png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
                                                               (png_uint_32)(png_sizeof(png_uint_16) * num_weights));

            png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
                                                                   (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
            for (i = 0; i < num_weights; i++)
            {
                png_ptr->inv_filter_weights[i] =
                    png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
            }
        }

        for (i = 0; i < num_weights; i++)
        {
            if (filter_weights[i] < 0.0)
            {
                png_ptr->inv_filter_weights[i] =
                    png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
            }
            else
            {
                png_ptr->inv_filter_weights[i] =
                    (png_uint_16)((double)PNG_WEIGHT_FACTOR * filter_weights[i] + 0.5);
                png_ptr->filter_weights[i] =
                    (png_uint_16)((double)PNG_WEIGHT_FACTOR / filter_weights[i] + 0.5);
            }
        }
    }

    /* If, in the future, there are other filter methods, this would
     * need to be based on png_ptr->filter.
     */
    if (png_ptr->filter_costs == NULL)
    {
        png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
                                                         (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));

        png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
                                                             (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));

        for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
        {
            png_ptr->inv_filter_costs[i] =
                png_ptr->filter_costs[i] = PNG_COST_FACTOR;
        }
    }

    /* Here is where we set the relative costs of the different filters.  We
     * should take the desired compression level into account when setting
     * the costs, so that Paeth, for instance, has a high relative cost at low
     * compression levels, while it has a lower relative cost at higher
     * compression settings.  The filter types are in order of increasing
     * relative cost, so it would be possible to do this with an algorithm.
     */
    for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
    {
        if (filter_costs == NULL || filter_costs[i] < 0.0)
        {
            png_ptr->inv_filter_costs[i] =
                png_ptr->filter_costs[i] = PNG_COST_FACTOR;
        }
        else if (filter_costs[i] >= 1.0)
        {
            png_ptr->inv_filter_costs[i] =
                (png_uint_16)((double)PNG_COST_FACTOR / filter_costs[i] + 0.5);
            png_ptr->filter_costs[i] =
                (png_uint_16)((double)PNG_COST_FACTOR * filter_costs[i] + 0.5);
        }
    }
}
    #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */

void PNGAPI
png_set_compression_level(png_structp png_ptr, int level)
{
    png_debug(1, "in png_set_compression_level");

    if (png_ptr == NULL)
        return;
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_LEVEL;
    png_ptr->zlib_level = level;
}

void PNGAPI
png_set_compression_mem_level(png_structp png_ptr, int mem_level)
{
    png_debug(1, "in png_set_compression_mem_level");

    if (png_ptr == NULL)
        return;
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL;
    png_ptr->zlib_mem_level = mem_level;
}

void PNGAPI
png_set_compression_strategy(png_structp png_ptr, int strategy)
{
    png_debug(1, "in png_set_compression_strategy");

    if (png_ptr == NULL)
        return;
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
    png_ptr->zlib_strategy = strategy;
}

void PNGAPI
png_set_compression_window_bits(png_structp png_ptr, int window_bits)
{
    if (png_ptr == NULL)
        return;
    if (window_bits > 15)
        png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
    else if (window_bits < 8)
        png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
    #ifndef WBITS_8_OK
    /* Avoid libpng bug with 256-byte windows */
    if (window_bits == 8)
    {
        png_warning(png_ptr, "Compression window is being reset to 512");
        window_bits = 9;
    }
    #endif
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS;
    png_ptr->zlib_window_bits = window_bits;
}

void PNGAPI
png_set_compression_method(png_structp png_ptr, int method)
{
    png_debug(1, "in png_set_compression_method");

    if (png_ptr == NULL)
        return;
    if (method != 8)
        png_warning(png_ptr, "Only compression method 8 is supported by PNG");
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_METHOD;
    png_ptr->zlib_method = method;
}

void PNGAPI
png_set_write_status_fn(png_structp png_ptr, png_write_status_ptr write_row_fn)
{
    if (png_ptr == NULL)
        return;
    png_ptr->write_row_fn = write_row_fn;
}

    #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
void PNGAPI
png_set_write_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
                                write_user_transform_fn)
{
    png_debug(1, "in png_set_write_user_transform_fn");

    if (png_ptr == NULL)
        return;
    png_ptr->transformations |= PNG_USER_TRANSFORM;
    png_ptr->write_user_transform_fn = write_user_transform_fn;
}
    #endif


    #ifdef PNG_INFO_IMAGE_SUPPORTED
void PNGAPI
png_write_png(png_structp png_ptr, png_infop info_ptr,
              int transforms, voidp params)
{
    if (png_ptr == NULL || info_ptr == NULL)
        return;

    /* Write the file header information. */
    png_write_info(png_ptr, info_ptr);

    /* ------ these transformations don't touch the info structure ------- */

    #ifdef PNG_WRITE_INVERT_SUPPORTED
    /* Invert monochrome pixels */
    if (transforms & PNG_TRANSFORM_INVERT_MONO)
        png_set_invert_mono(png_ptr);
    #endif

    #ifdef PNG_WRITE_SHIFT_SUPPORTED
    /* Shift the pixels up to a legal bit depth and fill in
     * as appropriate to correctly scale the image.
     */
    if ((transforms & PNG_TRANSFORM_SHIFT)
        && (info_ptr->valid & PNG_INFO_sBIT))
        png_set_shift(png_ptr, &info_ptr->sig_bit);
    #endif

    #ifdef PNG_WRITE_PACK_SUPPORTED
    /* Pack pixels into bytes */
    if (transforms & PNG_TRANSFORM_PACKING)
        png_set_packing(png_ptr);
    #endif

    #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    /* Swap location of alpha bytes from ARGB to RGBA */
    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
        png_set_swap_alpha(png_ptr);
    #endif

    #ifdef PNG_WRITE_FILLER_SUPPORTED
    /* Pack XRGB/RGBX/ARGB/RGBA into * RGB (4 channels -> 3 channels) */
    if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
        png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
    else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
        png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
    #endif

    #ifdef PNG_WRITE_BGR_SUPPORTED
    /* Flip BGR pixels to RGB */
    if (transforms & PNG_TRANSFORM_BGR)
        png_set_bgr(png_ptr);
    #endif

    #ifdef PNG_WRITE_SWAP_SUPPORTED
    /* Swap bytes of 16-bit files to most significant byte first */
    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
        png_set_swap(png_ptr);
    #endif

    #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
    /* Swap bits of 1, 2, 4 bit packed pixel formats */
    if (transforms & PNG_TRANSFORM_PACKSWAP)
        png_set_packswap(png_ptr);
    #endif

    #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
    /* Invert the alpha channel from opacity to transparency */
    if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
        png_set_invert_alpha(png_ptr);
    #endif

    /* ----------------------- end of transformations ------------------- */

    /* Write the bits */
    if (info_ptr->valid & PNG_INFO_IDAT)
        png_write_image(png_ptr, info_ptr->row_pointers);

    /* It is REQUIRED to call this to finish writing the rest of the file */
    png_write_end(png_ptr, info_ptr);

    transforms = transforms; /* Quiet compiler warnings */
    params = params;
}
    #endif
#endif /* PNG_WRITE_SUPPORTED */